How do you purge air from the Power Steering Pump?

[Russell J]

1972 F100 2WD

I've seen alot of different suggestions for bleeding air out of the power steering pump and lines. I just rebuilt my power steering pump and it's whining/grinding pretty bad. 99.9% sure it is air in the lines.

I've seen that you should jack up the front of the truck, top off the fluid and turn the wheel lock to lock several times. The differing opinions I see are whether you should have the engine running or not when you do this.

So what's the procedure? and is it engine running or off during the procedure?

Thanks folks!!

[HIO Silver]

Yup. I jack it up the truck and put 'er on stands with both wheels off the ground. Then I top off the PS reservoir and, with the belt loosened, manually spin the pulley... you can see the pump vanes work by the rise and fall of the fluid. I top it off til the level no longer drops and then set the belt tension.

At initial fire up, I turn the steering wheel lock to lock a couple of times and then shut off the engine as to not run the pump empty. Refill again. Run it again and repeat til I get a good wheel.

Btw. Ford/Thompson pumps have an Allen head which secures the pulley. Install the correct size allen in a drill/driver and use it to spin the pump.... 3/8ths?

There was one guy on a competing website for days couldn't purge his 78's 4x4 system until he disconnected the steering gear from the linkages and inverted it to purge the trapped air. Weird, eh?